lst = [1,20,8,2,9,18,3,4,5,6,7]
num1 = int(input("please input a number:"))
flag = 0
for i in range(len(lst)-1):
    for j in range(i+1, len(lst)):
        if lst[i] + lst[j] == num1:
            print(i, j)
            flag = 1
            break
        elif i == len(lst)-2 and j == i+1:
            print("没有查到")
    if flag == 1:
        break
